Curves: Rename "Hair" types, variables, and functions to "Curves"

Based on discussions from T95355 and T94193, the plan is to use
the name "Curves" to describe the data-block container for multiple
curves. Eventually this will replace the existing "Curve" data-block.
However, it will be a while before the curve data-block can be replaced
so in order to distinguish the two curve types in the UI, "Hair Curves"
will be used, but eventually changed back to "Curves".

This patch renames "hair-related" files, functions, types, and variable
names to this convention. A deep rename is preferred to keep code
consistent and to avoid any "hair" terminology from leaking, since the
new data-block is meant for all curve types, not just hair use cases.

The downside of this naming is that the difference between "Curve"
and "Curves" has become important. That was considered during
design discussons and deemed acceptable, especially given the
non-permanent nature of the somewhat common conflict.

Some points of interest:
- All DNA compatibility is lost, just like rBf59767ff9729.
- I renamed `ID_HA` to `ID_CV` so there is no complete mismatch.
- `hair_curves` is used where necessary to distinguish from the
  existing "curves" plural.
- I didn't rename any of the cycles/rendering code function names,
  since that is also used by the old hair particle system.

Differential Revision: https://developer.blender.org/D14007

1 files changed, 389 insertions, 0 deletions

diff --git a/source/blender/draw/intern/draw_cache_impl_curves.cc b/source/blender/draw/intern/draw_cache_impl_curves.cc
new file mode 100644
index 00000000000..8ec97495fcf
--- /dev/null
+++ b/source/blender/draw/intern/draw_cache_impl_curves.cc
@@ -0,0 +1,389 @@
+/*
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ * The Original Code is Copyright (C) 2017 by Blender Foundation.
+ * All rights reserved.
+ */
+
+/** \file
+ * \ingroup draw
+ *
+ * \brief Hair API for render engines
+ */
+
+#include <cstring>
+
+#include "MEM_guardedalloc.h"
+
+#include "BLI_listbase.h"
+#include "BLI_math_base.h"
+#include "BLI_math_vec_types.hh"
+#include "BLI_math_vector.h"
+#include "BLI_math_vector.hh"
+#include "BLI_span.hh"
+#include "BLI_utildefines.h"
+
+#include "DNA_curves_types.h"
+#include "DNA_object_types.h"
+
+#include "BKE_curves.h"
+
+#include "GPU_batch.h"
+#include "GPU_material.h"
+#include "GPU_texture.h"
+
+#include "draw_cache_impl.h"   /* own include */
+#include "draw_hair_private.h" /* own include */
+
+using blender::float3;
+using blender::IndexRange;
+using blender::Span;
+
+static void curves_batch_cache_clear(Curves *curves);
+
+/* ---------------------------------------------------------------------- */
+/* Hair GPUBatch Cache */
+
+struct HairBatchCache {
+  ParticleHairCache hair;
+
+  /* settings to determine if cache is invalid */
+  bool is_dirty;
+};
+
+/* GPUBatch cache management. */
+
+static bool curves_batch_cache_valid(Curves *curves)
+{
+  HairBatchCache *cache = static_cast<HairBatchCache *>(curves->batch_cache);
+  return (cache && cache->is_dirty == false);
+}
+
+static void curves_batch_cache_init(Curves *curves)
+{
+  HairBatchCache *cache = static_cast<HairBatchCache *>(curves->batch_cache);
+
+  if (!cache) {
+    cache = MEM_cnew<HairBatchCache>(__func__);
+    curves->batch_cache = cache;
+  }
+  else {
+    memset(cache, 0, sizeof(*cache));
+  }
+
+  cache->is_dirty = false;
+}
+
+void DRW_curves_batch_cache_validate(Curves *curves)
+{
+  if (!curves_batch_cache_valid(curves)) {
+    curves_batch_cache_clear(curves);
+    curves_batch_cache_init(curves);
+  }
+}
+
+static HairBatchCache *curves_batch_cache_get(Curves *curves)
+{
+  DRW_curves_batch_cache_validate(curves);
+  return static_cast<HairBatchCache *>(curves->batch_cache);
+}
+
+void DRW_curves_batch_cache_dirty_tag(Curves *curves, int mode)
+{
+  HairBatchCache *cache = static_cast<HairBatchCache *>(curves->batch_cache);
+  if (cache == nullptr) {
+    return;
+  }
+  switch (mode) {
+    case BKE_CURVES_BATCH_DIRTY_ALL:
+      cache->is_dirty = true;
+      break;
+    default:
+      BLI_assert(0);
+  }
+}
+
+static void curves_batch_cache_clear(Curves *curves)
+{
+  HairBatchCache *cache = static_cast<HairBatchCache *>(curves->batch_cache);
+  if (!cache) {
+    return;
+  }
+
+  particle_batch_cache_clear_hair(&cache->hair);
+}
+
+void DRW_curves_batch_cache_free(Curves *curves)
+{
+  curves_batch_cache_clear(curves);
+  MEM_SAFE_FREE(curves->batch_cache);
+}
+
+static void ensure_seg_pt_count(Curves *curves, ParticleHairCache *curves_cache)
+{
+  if ((curves_cache->pos != nullptr && curves_cache->indices != nullptr) ||
+      (curves_cache->proc_point_buf != nullptr)) {
+    return;
+  }
+
+  curves_cache->strands_len = curves->geometry.curve_size;
+  curves_cache->elems_len = curves->geometry.point_size + curves->geometry.curve_size;
+  curves_cache->point_len = curves->geometry.point_size;
+}
+
+static void curves_batch_cache_fill_segments_proc_pos(Curves *curves,
+                                                      GPUVertBufRaw *attr_step,
+                                                      GPUVertBufRaw *length_step)
+{
+  /* TODO: use hair radius layer if available. */
+  const int curve_size = curves->geometry.curve_size;
+  Span<int> offsets{curves->geometry.offsets, curves->geometry.curve_size + 1};
+
+  Span<float3> positions{(float3 *)curves->geometry.position, curves->geometry.point_size};
+
+  for (const int i : IndexRange(curve_size)) {
+    const IndexRange curve_range(offsets[i], offsets[i + 1] - offsets[i]);
+
+    Span<float3> spline_positions = positions.slice(curve_range);
+    float total_len = 0.0f;
+    float *seg_data_first;
+    for (const int i_spline : spline_positions.index_range()) {
+      float *seg_data = (float *)GPU_vertbuf_raw_step(attr_step);
+      copy_v3_v3(seg_data, spline_positions[i_spline]);
+      if (i_spline == 0) {
+        seg_data_first = seg_data;
+      }
+      else {
+        total_len += blender::math::distance(spline_positions[i_spline - 1],
+                                             spline_positions[i_spline]);
+      }
+      seg_data[3] = total_len;
+    }
+    /* Assign length value. */
+    *(float *)GPU_vertbuf_raw_step(length_step) = total_len;
+    if (total_len > 0.0f) {
+      /* Divide by total length to have a [0-1] number. */
+      for ([[maybe_unused]] const int i_spline : spline_positions.index_range()) {
+        seg_data_first[3] /= total_len;
+        seg_data_first += 4;
+      }
+    }
+  }
+}
+
+static void curves_batch_cache_ensure_procedural_pos(Curves *curves,
+                                                     ParticleHairCache *cache,
+                                                     GPUMaterial *gpu_material)
+{
+  if (cache->proc_point_buf == nullptr) {
+    /* initialize vertex format */
+    GPUVertFormat format = {0};
+    uint pos_id = GPU_vertformat_attr_add(&format, "posTime", GPU_COMP_F32, 4, GPU_FETCH_FLOAT);
+
+    cache->proc_point_buf = GPU_vertbuf_create_with_format(&format);
+    GPU_vertbuf_data_alloc(cache->proc_point_buf, cache->point_len);
+
+    GPUVertBufRaw point_step;
+    GPU_vertbuf_attr_get_raw_data(cache->proc_point_buf, pos_id, &point_step);
+
+    GPUVertFormat length_format = {0};
+    uint length_id = GPU_vertformat_attr_add(
+        &length_format, "hairLength", GPU_COMP_F32, 1, GPU_FETCH_FLOAT);
+
+    cache->proc_length_buf = GPU_vertbuf_create_with_format(&length_format);
+    GPU_vertbuf_data_alloc(cache->proc_length_buf, cache->strands_len);
+
+    GPUVertBufRaw length_step;
+    GPU_vertbuf_attr_get_raw_data(cache->proc_length_buf, length_id, &length_step);
+
+    curves_batch_cache_fill_segments_proc_pos(curves, &point_step, &length_step);
+
+    /* Create vbo immediately to bind to texture buffer. */
+    GPU_vertbuf_use(cache->proc_point_buf);
+    cache->point_tex = GPU_texture_create_from_vertbuf("hair_point", cache->proc_point_buf);
+  }
+
+  if (gpu_material && cache->proc_length_buf != nullptr && cache->length_tex) {
+    ListBase gpu_attrs = GPU_material_attributes(gpu_material);
+    LISTBASE_FOREACH (GPUMaterialAttribute *, attr, &gpu_attrs) {
+      if (attr->type == CD_HAIRLENGTH) {
+        GPU_vertbuf_use(cache->proc_length_buf);
+        cache->length_tex = GPU_texture_create_from_vertbuf("hair_length", cache->proc_length_buf);
+        break;
+      }
+    }
+  }
+}
+
+static void curves_batch_cache_fill_strands_data(Curves *curves,
+                                                 GPUVertBufRaw *data_step,
+                                                 GPUVertBufRaw *seg_step)
+{
+  const int curve_size = curves->geometry.curve_size;
+  Span<int> offsets{curves->geometry.offsets, curves->geometry.curve_size + 1};
+
+  for (const int i : IndexRange(curve_size)) {
+    const IndexRange curve_range(offsets[i], offsets[i + 1] - offsets[i]);
+
+    *(uint *)GPU_vertbuf_raw_step(data_step) = curve_range.start();
+    *(ushort *)GPU_vertbuf_raw_step(seg_step) = curve_range.size() - 1;
+  }
+}
+
+static void curves_batch_cache_ensure_procedural_strand_data(Curves *curves,
+                                                             ParticleHairCache *cache)
+{
+  GPUVertBufRaw data_step, seg_step;
+
+  GPUVertFormat format_data = {0};
+  uint data_id = GPU_vertformat_attr_add(&format_data, "data", GPU_COMP_U32, 1, GPU_FETCH_INT);
+
+  GPUVertFormat format_seg = {0};
+  uint seg_id = GPU_vertformat_attr_add(&format_seg, "data", GPU_COMP_U16, 1, GPU_FETCH_INT);
+
+  /* Strand Data */
+  cache->proc_strand_buf = GPU_vertbuf_create_with_format(&format_data);
+  GPU_vertbuf_data_alloc(cache->proc_strand_buf, cache->strands_len);
+  GPU_vertbuf_attr_get_raw_data(cache->proc_strand_buf, data_id, &data_step);
+
+  cache->proc_strand_seg_buf = GPU_vertbuf_create_with_format(&format_seg);
+  GPU_vertbuf_data_alloc(cache->proc_strand_seg_buf, cache->strands_len);
+  GPU_vertbuf_attr_get_raw_data(cache->proc_strand_seg_buf, seg_id, &seg_step);
+
+  curves_batch_cache_fill_strands_data(curves, &data_step, &seg_step);
+
+  /* Create vbo immediately to bind to texture buffer. */
+  GPU_vertbuf_use(cache->proc_strand_buf);
+  cache->strand_tex = GPU_texture_create_from_vertbuf("curves_strand", cache->proc_strand_buf);
+
+  GPU_vertbuf_use(cache->proc_strand_seg_buf);
+  cache->strand_seg_tex = GPU_texture_create_from_vertbuf("curves_strand_seg",
+                                                          cache->proc_strand_seg_buf);
+}
+
+static void curves_batch_cache_ensure_procedural_final_points(ParticleHairCache *cache, int subdiv)
+{
+  /* Same format as point_tex. */
+  GPUVertFormat format = {0};
+  GPU_vertformat_attr_add(&format, "pos", GPU_COMP_F32, 4, GPU_FETCH_FLOAT);
+
+  cache->final[subdiv].proc_buf = GPU_vertbuf_create_with_format_ex(&format,
+                                                                    GPU_USAGE_DEVICE_ONLY);
+
+  /* Create a destination buffer for the transform feedback. Sized appropriately */
+  /* Those are points! not line segments. */
+  GPU_vertbuf_data_alloc(cache->final[subdiv].proc_buf,
+                         cache->final[subdiv].strands_res * cache->strands_len);
+
+  /* Create vbo immediately to bind to texture buffer. */
+  GPU_vertbuf_use(cache->final[subdiv].proc_buf);
+
+  cache->final[subdiv].proc_tex = GPU_texture_create_from_vertbuf("hair_proc",
+                                                                  cache->final[subdiv].proc_buf);
+}
+
+static void curves_batch_cache_fill_segments_indices(Curves *curves,
+                                                     const int res,
+                                                     GPUIndexBufBuilder *elb)
+{
+  const int curve_size = curves->geometry.curve_size;
+
+  uint curr_point = 0;
+
+  for ([[maybe_unused]] const int i : IndexRange(curve_size)) {
+    for (int k = 0; k < res; k++) {
+      GPU_indexbuf_add_generic_vert(elb, curr_point++);
+    }
+    GPU_indexbuf_add_primitive_restart(elb);
+  }
+}
+
+static void curves_batch_cache_ensure_procedural_indices(Curves *curves,
+                                                         ParticleHairCache *cache,
+                                                         int thickness_res,
+                                                         int subdiv)
+{
+  BLI_assert(thickness_res <= MAX_THICKRES); /* Cylinder strip not currently supported. */
+
+  if (cache->final[subdiv].proc_hairs[thickness_res - 1] != nullptr) {
+    return;
+  }
+
+  int verts_per_hair = cache->final[subdiv].strands_res * thickness_res;
+  /* +1 for primitive restart */
+  int element_count = (verts_per_hair + 1) * cache->strands_len;
+  GPUPrimType prim_type = (thickness_res == 1) ? GPU_PRIM_LINE_STRIP : GPU_PRIM_TRI_STRIP;
+
+  static GPUVertFormat format = {0};
+  GPU_vertformat_clear(&format);
+
+  /* initialize vertex format */
+  GPU_vertformat_attr_add(&format, "dummy", GPU_COMP_U8, 1, GPU_FETCH_INT_TO_FLOAT_UNIT);
+
+  GPUVertBuf *vbo = GPU_vertbuf_create_with_format(&format);
+  GPU_vertbuf_data_alloc(vbo, 1);
+
+  GPUIndexBufBuilder elb;
+  GPU_indexbuf_init_ex(&elb, prim_type, element_count, element_count);
+
+  curves_batch_cache_fill_segments_indices(curves, verts_per_hair, &elb);
+
+  cache->final[subdiv].proc_hairs[thickness_res - 1] = GPU_batch_create_ex(
+      prim_type, vbo, GPU_indexbuf_build(&elb), GPU_BATCH_OWNS_VBO | GPU_BATCH_OWNS_INDEX);
+}
+
+bool hair_ensure_procedural_data(Object *object,
+                                 ParticleHairCache **r_hair_cache,
+                                 GPUMaterial *gpu_material,
+                                 int subdiv,
+                                 int thickness_res)
+{
+  bool need_ft_update = false;
+  Curves *curves = static_cast<Curves *>(object->data);
+
+  HairBatchCache *cache = curves_batch_cache_get(curves);
+  *r_hair_cache = &cache->hair;
+
+  const int steps = 2; /* TODO: don't hard-code? */
+  (*r_hair_cache)->final[subdiv].strands_res = 1 << (steps + subdiv);
+
+  /* Refreshed on combing and simulation. */
+  if ((*r_hair_cache)->proc_point_buf == nullptr) {
+    ensure_seg_pt_count(curves, &cache->hair);
+    curves_batch_cache_ensure_procedural_pos(curves, &cache->hair, gpu_material);
+    need_ft_update = true;
+  }
+
+  /* Refreshed if active layer or custom data changes. */
+  if ((*r_hair_cache)->strand_tex == nullptr) {
+    curves_batch_cache_ensure_procedural_strand_data(curves, &cache->hair);
+  }
+
+  /* Refreshed only on subdiv count change. */
+  if ((*r_hair_cache)->final[subdiv].proc_buf == nullptr) {
+    curves_batch_cache_ensure_procedural_final_points(&cache->hair, subdiv);
+    need_ft_update = true;
+  }
+  if ((*r_hair_cache)->final[subdiv].proc_hairs[thickness_res - 1] == nullptr) {
+    curves_batch_cache_ensure_procedural_indices(curves, &cache->hair, thickness_res, subdiv);
+  }
+
+  return need_ft_update;
+}
+
+int DRW_curves_material_count_get(Curves *curves)
+{
+  return max_ii(1, curves->totcol);
+}